Morphological and molecular insights on Megalothorax: the largest Neelipleona genus revisited (Collembola)

The genus Megalothorax Willem, 1900 is redefined along with a redescription of the type species M. minimus Willem, 1900 and the description of five new species (M. granulosus, sp. nov., M. nigropunctatus, sp. nov., M. perspicillum, sp. nov., M. svalbardensis, sp. nov. and M. willemi, sp. nov.). We describe and comment on broad sets of discriminating characters for Megalothorax systematics. For the first time, trichobothria are recorded for Neelipleona, probably of generic importance. The described species are provided with DNA data (COI, 16S and 28S) and included in a molecular-based phylogenetic analysis. The traditional distinction between minimus-group and incertus-group is discussed in the light of DNA and morphology components. A key to the worldwide Megalothorax species is provided.